According to the prior art, enclosures, particularly for shipboard installation, are provided in the form of a cabinet having two vertically elongated side panels joined to removable top, bottom, front and rear plates. The cabinets must be strong and rigid when assembled and yet easily disassembled and broken down to a small component size for installation, transportation and storage. When installed, the cabinets are secured to the deck or other rigid structure such that the bottom plate and lower portions of the side panels are not substantially disturbed by induced vibration or other externally induced accelerations. However the central and upper portions of the side panels would be induced to oscillate in a generally horizontally mode in response to vibrational excitation unless sufficiently rigid interconnecting plates are firmly secured between the side panels to prevent such movement.
According to conventional practice, the plates have sufficient rigidity and strength to absorb the forces generated between the opposing side panels. In the usual case, the plates are secured to the side panels with screw type fasteners, such as a bolt received through a bore in the plates and into a threaded bore in the side panels. A combination of friction between the mating surfaces on the plates and panels, together with a close interfitting relationship in the bore between the fastener and plate, is relied upon for the transfer of shear forces between the side panels and plates.
An interconnection system as described above may be satisfactory for relatively low vibrational amplitudes and frequencies. However, it has been found that according to conventional practice it is not possible to satisfactorily sustain a proper stress transfer relationship between the plates and panels undergoing standarized tests above approximately 35 Hertz and acceleration of 3G. Above this frequency and force loading, flat surface metal to metal friction is insufficient and the plate and panel begin to move relatively to one another. Under particularly unfavorable circumstances, these oscillations may increase to the point of damage or destruction to the cabinet itself and are even more likely to damage or destroy the electronics assemblies with the cabinet. The performance of such a cabinet further deteriorates if it has been previously subjected to high shock loadings.
It has been proposed that an improved shear transfer relationship could be developed by precisely milled notches and corresponding projections on the plates and panels, and by the use of precision fitted fasteners. However, such techniques have not proved to be practical because the tolerances required cannot be maintained in the field. Further, precision fit fasteners are expensive to produce and difficult to install and remove.
It is therefore desirable to have a cabinet assembly that transfers the shear force induced by high shock loadings and by vibration at frequencies in excess of 35 Hertz. Such an assembly is particularly desirable if the mating surfaces of the component parts to not require close tolerances and where the parts may be easily assembled and disassembled.